VERY odd problem... HALF a power outage??

Ok, let me start by saying that I am not an electrician... but a very avid DIY'er, with more than a little Electronics background.... And I've been 'lurking' the forums on this site, and enjoying the massive wealth of information for many many months.... Well, now I've got a problem that has me VERY much stumped, and I'm hoping that someone else has a clue at least what might be going on!

About 5 months ago, we moved into a new house, and everything is pretty much dandy except this one re-occuring problem. Infrequently, I seem to be having half a power outage! When it happens, basically half of the circuits in the house will lose power... though half will REMAIN powered. No breakers trip, no other signs of anything unusual at the panel... but everything on one side of the 220V split seems to be out. This has happened three times now.

To make things more interesting, I've proven what seems to be an odd-ball clue to the entire equation: if I power on my dryer, and actually START it cycling, IMMEDIATELY power comes back. I say 'proven', because the first time power came back after about 1/2 an hour of testing outlets and fuxtires (with a VOM) , power came back as I was testing to see if the dryer was 'functional'... though I don't believe the dryer had been 'running' while power was off. The washer had been, however.

When the same problem reoccured (probably 4-6 weeks later?), I was actually running the dryer at the time (but not the washer, I don't think), and quite a few other applicances (the wife and I were cooking because we were expecting company shortly)... THIS time, I went straight to the dryer... powered it on, started a cycle, and power IMMEDIATELY came back.

Well... this morning (about 2-3 weeks later?) it happened again, JUST as I was about to leave for work. My wife had just started a load of laundry in the washer.. (the dryer was not on). She turned on a light switch in one room, and it didn't come on for more than a split second - and I noticed out of the corner of my eye that the kitchen circuit seemed to go down as well. Sure enough, another 'Half outage'... no circuits tripped, etc.... walked directly to the dryer, powered it up, started a 'cycle', and everything immediately came back to life. Again.

3rd time duplicating this 'solution' tells me there HAS to be a clue here, and I'm just not seeing it.... Anyone out there have any thoughts??

The main breaker could be bad. Sounds like you have an intermittent connection to one of the bus bars, which could be the breaker or the lead to it. It could also be a panel problem. Playing with a panel, especially the main breaker, may not be something you want to deal with. To change the main breaker, you'd probably have to (or have it done) pull the meter base so you can work on the panel without power applied. This is probably not something you would want to do yourself - time for a pro.

If you have any other 220vac devices in the house, turning one of them on probably would have done the same thing. The dryer may not work properly, but it would be backfeeding power to the other half of the panel. The dryer might only have 110-120vac present (i.e., from one half of the power). The motor in the dryer is likely 110v, so it could run if it was on the available phase, but the heating elements wouldn't get to the proper temp since it is missing the input.

this could quickly burn out 220vac motors, though (say in an a/c compressor or the air handler portion of a furnace).

The power coming into the house is all 220-240vac. If you were to place a contact half-way across the secondary coil of the transformer, you'd get a point that was at zero volts or 110-120vac relative to each end. That point becomes the neutral.

Thanks for the responses! Ok... I think I see where you're both going on this one.... hadn't really thought of that!

So let me make sure I'm at least following properly: If it is an intermittent / loose connection, and the voltage is backfeeding through the dryer itself (because it encompasses the entire 220-240V circuit), wouldn't that mean that the 'half' of the panel which is 'going out' is, after turning on the dryer of course, drawing the entire load of the circuit through the dryer? And if the dryer motor is 110V and only the heating element(s) are 220/240... wouldn't that mean that they are sourcing the entire current load of that portion of the circuit through itself? And if that was the case... wouldn't the circuit be broken when the device is shut off (Because in two of the three cases, the dryer wasn't running before the outage, so I didn't keep it running after it 'fixed' the outage)? Do you think that maybe a loose / intermittent connection could be causing an arc-draw of current, creating and keeping the circuit (just my musings)?

Hmm... I don't believe I have any other 220-240V circuits in the house besides the stove/oven (which goes out completely, though whether due to the control panel just being on the 'wrong' side of the 220-240V split, who knows)... and besides that, a circuit that formerly fed a Hot tub that the prior owner had. I actually think my furnace's motor is 110V, though I will have to double-check that tonight! Hmmm... and come to think of it, I believe I actually have a 220-240V feed going to the sub-panel in my garage/workshop, though I've never actually examined or mapped that circuit out. Another thing to check tonight!

I'm familiar with pulling the meter base... (remodel of prior house... in which my work did, thankfully, pass code/inspection ) which would absolutely be necessary in this case, because my main panel is older, and I don't believe it actually HAS a main breaker; I think it has a split-bus bar, or something, with circuits looped back through a regular breaker briding that split (again, haven't examined it too closely... add to my 'to-do' list)!

So thinking proactively here, I want to come up with my 'plan of action' the next time this actually happens.... and here's what I have so far:

P.S. Your electric company may say everything including the meter base is your responsibility. But if they do come out and check their end, then at least you would know the trouble is with your equipment.

Definitely not red... I've only seen the inside of my panel once, actually (during the pre-purchase inspection), and I would have remembered it. I do have a near-photographic memory... and that would have stuck. Like I said, I don't think it actually HAS a main breaker... (one reason why one of my LONG-term goals is to completely replace the panel with a newer one... but that will require much saving of sheckels... )

I would advise you to first call your electric company and have them check/re-torque your main connections.

I would advise you to stay away from the panel.

Click to expand...

So you both think it is reasonable for me to make a request like that of the power company? Or just describe the problem, and see what they will do (within their 'responsibility', be it to the pole, utility side of meter base, etc.)? Don't worry... I'm very comfortable with at least *looking* inside the panel, and visually determining approximately what is where... Just definitely won't poke or prod around much unless I'm completely certain what I'm doing!

It sounds like the load from the dryer is causing a temporary arc weld wherever it's going bad.

Next time try turning off the main breaker and then back on again.

The problem is most likely between the pole transformer and the breakers in the panel.
1. The Utility transformer could be going bad. (not likely)
2. Underground wires can open up. (not likely, but I've seen it happen)
3. Meter lugs could have loosened up. (not likely)
4. Main panel lugs could have loosened up. (not likely)
5. Main breaker is bad. (This is where I'd place my bet)

This leaves 3 out of 5 possible spots in the power utility's area.

Personally. I like to tap, move, wiggle things to find bad connections. But I would not "recommend" others do that.

Well sometimes it is a power company problem. Once I saw an underground transformer supplying apartment buildings in a neighborhood lose one leg and everybody have half their power go out. In this case multiple buildings had the same problem.

Then a common problem is loose main connections. The main lugs in a meter base or panel carry a LOT of amperage. These need to be torqued with a torque wrench to make a good enough connection. The panel label will specify how tight in foot pounds the lugs should be tightened. (Hand tight will not cut it!)

If they are not tight enough, the connection can become warm or hot. Then you can get a cycle of cold/hot, cold/hot. After many years, I think this can cause the connections to loosen more.

Also aluminum wiring is frequently used for main connections. This wire will oxidize if anti-oxidant "goop" is not applied at installation.

So if someone installed aluminum wire, did not apply anti-oxidant goop, and did not torque the lugs tight enough, then this could be the cause of your problem.

Then there are problems with breakers and panels. There can be a poor connection from a main breaker to the bus, then this can get quite hot and damage surrounding components.

Hmm... Makes sense, because an inadequate connection could cause not visible arc'ing under heavy load.. which would definitely cause heat... Like I said, none of my breakers are actually tripping... but I'd imagine I will be able to detect the heat level. I'll use my no-contact laser/ir thermometer along with my visual inspection to check for abnormal heat levels at any connection / breaker. (VERY handy tool -- use it frequently during design and troubleshooting of component electronics circuits...)

Wow -- that is quite a story that you link'd in! I actually would never have thought to wear safety glasses when doing this sort of thing! But it is a very good point... Insulated tools is definitely a no-brainer, but wouldn't have really thought of other necessary PPE. Thanks for sharing!

...I will be able to detect the heat level. I'll use my no-contact laser/ir thermometer along with my visual inspection to check for abnormal heat levels at any connection / breaker. (VERY handy tool -- use it frequently during design and troubleshooting of component electronics circuits...)

Click to expand...

There ya go! That should help pinpoint problems. Also you can *carefully* measure connections with a voltmeter. Of course if it is a good connection, you would not get any reading.

Ok -- I know this is something of a ressurection, but I wanted to post and say that the problem HAS been solved... and in case anyone has a similar problem, knows what our circumstances involved.

Everyone's suggestion that the meter-main lugs may not have been completely snugged down, or may have worked themselves loose was close.... Here's the story!

Puget Sound Energy, our local power supplier, refused to send someone out to check the meter mains connection -- said it was our responsibility.

Soo, even though I know my way around electronics and the basics of electricity, not wanting to risk touching the meter box myself, I called an electrician recommended by a friend.. who came to a similar conclusion on his own, and immediately removed the meter.

Turns out that one of the hot wires was not just loose -- the LUG itself was broken off, and the wire was simply *sitting against the electrical contact!* This was most likely due to the fact that the power mast (going straight up from the meter box) was just at the edge of the 2ft height above roof surface - and the installing technician when the electrical was upgraded last did NOT put supports on the mast (in fact, did not even drill the hole through the sub-roofing tightly to match the diamater of the mast itself, either).. causing it to be able to move around.

So, cutting to the chase, I had them replace the meter box, mast, et al -- including the entire breaker panel with a brand-new Square-D model (something I knew I wanted to do long-term, but decided to bite the bullet and have them do it all at once to save some redundant costs)... Problem solved. And not a moment too soon! When removing the old meter box and wire up the mast, they noticed that about 4 strands of the copper wire used as mains from the pole transformer had literally welded themselves to the contact! And were VERY very stiff... even with my experience, I know that not only to be a sign of age.. but also probably quite extreme heat, probably caused by arc'ing! This could very well have ended much more tragically with a fire, or something else.

So thanks to all who advised me in this -- much appreciated! Hope this information can help point anyone with a similar problem in the future in the right direction!

ok not an electrician or a great speller either so bare with me.... OK so a 220 plug to a drier is just 2 110 lines. so if the person who installed the wires in the house split one of the 110 lines to run the rest or part of the house. you could just be over loading on side of the 220. so turning the drier on loop's the one side of the 220 that is still hot to the side that has blown. i have a fuse box and have had this prob for about 3 months now. half of the house goes out but if i turn the drier on it spins but no heat and the rest of the house comes back on. so my quick fix ides is to take the 220 plug and swap the two hot wires. maybe the heat coil and the rest of the house is blowing my fuses and not the round screw in type the one that are about 3" long and round as a nickle. could this maybe work? i always thought every 220 was just to one outlet not split to power half of the houses 110, am i right on that at least? and why would it not blow the large fuses before the small screw in type?

quote; And if that was the case... wouldn't the circuit be broken when the device is shut off (Because in two of the three cases, the dryer wasn't running before the outage, so I didn't keep it running after it 'fixed' the outage)?

If your diagnosis is correct, ANY 220/240 device, such as an air conditioner or electric heat device, would cause the same symptoms if it were to turn on.

I had an intermittent loss of power problem in my house that took years to develop and get bad enough to find. The house is a 2 family duplex I have owned and lived in for over 40 years. It has 2 meters into one pan and each side is fed from there. Both sides have 100 amp panels. One side....the one I live in has a 100 amp breaker mounted in a weatherproof box directly under the meter pan. The side where the meter is has the main in the 100 amp panel directly inside from the meters. The outside main is necessary because of the distance to my sides panel.
I was occasionally having loss of power or dimming of some lights....on my side only. A good freind is/was a lifelong electrician. We investigated and decided to replace the 100 amp breaker thinking maybe it was the problem since it was outside. Some time later the problem got worse....so we attemted again to find the issue. We still could not find the issue until one day power failed while we were standing and just talking in my garage......We eventually found the problem and made a repair. The meter for my side had a loose screw that holds the clips where the meter plugs in. It had arced for so long the threads for the screw hole were gone. Arcing had ruined them and one side of the meter lost contact with the bar. The bars are there to mount the meters and feed both sides from the service cable. My friend used a cordless drill and drilled and tapped the hole for a larger screw in the bar. We then modified the clip for the bigger screw and got it all back together and HE did the entire job with the service still connected.....I was not real comfortable doing this but he was and we were extremely carefull.

That repair lasted for years untill one day my service cables were cut and laying in the street....I assumed a truck caught them as it passed and the driver never knew it. The severed cables were still live and just laying in the street at the curb....no arcing....

I had the entire service replaced as this was a perfect opportunity to get rid of that old meter pan......and this was done once before in 1978.....so that meter pan and the service cable was 30 years old......A storm ripped it off in 1978 and everything replaced back then......The arcing and loose screw issue went on for a few years before it got so bad the power completely failed on one leg of my sides service only.....

The only way to find things like this is to disassmble items and look for evidence of problems....or possibly use a heat gun to find higher temps.....or in our case we actually heard the arcing at the meter when we removed it and pushed it back in....We did not see the issue untill we heard that arcing....

None of this should be done by anyone but an electrician or the power company to check your meter and service cable connections....

Depending on where you live, breaking the seal and removing the meter can get you hit with a BIG fine. Thieves tend to do this, bridge across the thing and steal power without the meter reading what was used. Always check with the power company to find out what's required if the meter needs to be removed (which requires breaking the seal).

Depending on where you live, breaking the seal and removing the meter can get you hit with a BIG fine. Thieves tend to do this, bridge across the thing and steal power without the meter reading what was used. Always check with the power company to find out what's required if the meter needs to be removed (which requires breaking the seal).

Click to expand...

While I expect most electrical contractors in this area unlock meters themselves (I have seen all the keys on sale at most professional supply houses) I don't bother. I generally can get which ever power company that has jurisdiction to unlock a meter for me pretty quickly. If there is an actual emergency with snapping and crackling in the service panel, and odd activity in the juice coming out, then I just tell them to hurry up, and I have never been disappointed.

Now, of course, if there has been an earthquake or a really big windstorm, that may not hold.